1. Field of the Invention
This invention relates to a magnetic tape cartridge comprising a cartridge casing formed by upper and lower casing halves and a single reel around which a magnetic tape is wound and which is contained in the cartridge casing for rotation, and more particularly to such as magnetic tape cartridge provided with a slide door for opening and closing a tape outlet opening formed in the cartridge casing.
2. Description of the Related Art
There has been known a single reel magnetic tape cartridge comprising a flat cartridge casing which is formed by upper and lower casing halves and is substantially square in shape and a single reel around which a magnetic tape is wound and which is contained in the cartridge casing for rotation. Such a single reel magnetic tape cartridge has been used for retaining data of a computer or the like. A tape outlet opening is formed in a side wall of the cartridge casing and when the magnetic tape cartridge is used, i.e., when the magnetic tape cartridge is loaded in a recording and reproducing system as, for instance, an external storage for a computer and information is to be recorded on the magnetic tape or information recorded on the magnetic tape is to be read, the magnetic tape wound around the reel is drawn out through the tape outlet opening.
In such a magnetic tape cartridge of one type, a leader block is fixed to the leading end of a leader tape which is connected to the magnetic tape and when the magnetic tape cartridge is not used, the magnetic tape is fully wound around the reel with the leader block fitted in the tape outlet opening to close the tape outlet opening. In the case of the magnetic tape cartridge of this type, when the magnetic tape cartridge is loaded in the recording and reproducing system, a drive means in the recording and reproducing system engages with engagement teeth on the reel exposed outside at the central portion of the lower casing half and a tape drawing mechanism in the recording and reproducing system chucks the leader block and draws the magnetic tape outside the cartridge casing into a tape running path of the recording and reproducing system.
In another type, the tape outlet opening is closed and opened by a lid which is rotatable between a closing position where it closes the tape outlet opening and an opening position where it opens the tape outlet opening, the lid being urged by a spring toward the closing position and locked in the closing position by a lid lock spring-urged in the lock position. A hook member is fixed to the leading end of a leader tape which is connected to the magnetic tape and when the magnetic tape cartridge is not used, the magnetic tape is fully wound around the reel with the hook member retracted inside the tape outlet opening and the lid held in the closing position. In the case of the magnetic tape cartridge of this type, when the magnetic tape cartridge is loaded in the recording and reproducing system, a drive means in the recording and reproducing system engages with engagement teeth on the reel exposed outside at the central portion of the lower casing half and a tape drawing mechanism in the recording and reproducing system moves the lid to the opening position, chucks the hook member and draws the magnetic tape outside the cartridge casing into a tape running path of the recording and reproducing system.
The magnetic tape cartridge of the former type is advantageous in that the tape drawing mechanism of the tape drive system may be simple in structure since the tape drawing mechanism has only to chuck the leader block and draws the same. However there is a problem that dust is apt to enter the cartridge casing through the space between the leader block and the tape outlet opening when the magnetic tape cartridge is not used.
Though being free from the problem that dust is apt to enter the cartridge casing, the magnetic tape cartridge of the latter type is disadvantageous in that the lid lock must be released and the lid must be opened, which complicates the structure of the tape drawing mechanism. Further the space for rotating the lid is required in the tape drive system, and at the same time, incorporation of the springs for urging the lid and the lid lock in the cartridge casing takes a large man-hour.
In view of the foregoing observations and description, the primary object of the present invention is to provide a magnetic tape cartridge which is free from all the problems described above.
In accordance with the present invention, there is provided a magnetic tape cartridge comprising a cartridge casing formed by upper and lower casing halves and a single reel around which a magnetic tape is wound and which is contained in the cartridge casing for rotation, wherein the improvement comprises that a slide door for opening and closing a tape outlet opening is mounted on the cartridge casing to be linearly slidable along a passage between a closing position where it closes the tape outlet opening and an opening position where it opens the tape outlet opening, and a door spring for urging the slide door toward the closing position and holding the same in the closing position is disposed on the passage of the slide door.
With this arrangement, the fear that dust enters the cartridge casing through the tape outlet opening while the magnetic tape cartridge is not used can be eliminated, and no space for permitting the slide door to move to the opening position is necessary in the tape drive system.
Further since the slide door is simply held in the closed position by the door spring, the slide door can be opened by simply pushing the door overcoming the force of the door spring without releasing a lock, whereby the tape drawing mechanism may be simple in structure.
In one embodiment of the present invention, guide grooves for guiding the upper end lower ends of the slide door along the passage are formed respectively on the upper and lower casing halves and the door spring is in the form of a wire spring or a plate spring which is held between the upper and lower casing halves at one end and abuts against the rear end face of the slide door at the other end.
A wall portion which prevents the door spring from being disengaged from the slide door while the slide is slid between the opening position and the closing position may be provided on the cartridge casing.
With this arrangement, incorporation of the door spring is facilitated.
In another embodiment of the present invention, a closed space defining the passage of the slide door is formed between the upper and lower casing halves and the rear end face of the slide door and the door spring in the form of a plate spring is disposed in the closed space with its ends in abutment against the end wall of the closed space and the rear end face of the slide door, respectively.
With this embodiment, the door spring may be simply thrown in the closed space, and accordingly incorporation of the door spring is extremely facilitated.
The door spring may be a coiled spring whose longitudinal axis extends in parallel to the direction of sliding movement of the slide door. In this case, it is preferred that the coiled spring be disposed in a space surrounded by ribs respectively extending from the upper and lower casing halves. With this arrangement, the door spring can be held in place.
Further it is preferred that a bent portion against which the coiled spring abuts be formed on a rear end portion of the slide door. With this arrangement, the coiled spring can be surely abuts against the slide door.